synaptic transmission

• 1. nerve impulse arrives at pre synaptic terminal, causing synaptic vesicles to travel down to pre synaptic membrane
  2. pre synaptic vesicles fuse w pre synaptic membrane and release neurotransmitters into synaptic cleft
  3. neurotransmitters diffuse across synaptic cleft towards post synaptic terminal
  4. neurotransmitters bind to receptors on post synaptic terminal allowing positive particles to flow in it
  5. neurotranmistters flow into synaptic cleft and are taken up by reuptake proteins on pre synaptic membrane
• the more neurotransmitters that are released by pre synaptic neuron.....

  -the more neurotransmitters that will bind to receptors

  -the bigger the change in voltage

  -the more likely a nerve impulse is generated

  -the more positively charged particles will enter the neuron
• summation


  -occurs when multiple nerve impulses occur in pre synaptic neuron in CLOSE succession

  this triggers successive, fast changes in voltage in the post synaptic neuron

  -also occurs if multiple nerve impulses occur from diff synapses at same time
• excitatory and inhibitory neurotransmitters

  excitatory- cause positive particles to enter post synaptic neuron and increase voltage - makes nerve impulse MORE likely to occur

  inhibitory- cause negative particles to enter post synaptic neuron and decrease voltage- makes nerve impulse LESS likely to occur
• summation of excitatory and inhibitory neurotransmitters cancels out and nervous impulse LESS likely occur
• types of neurotransmitters


  -Acetylcholine-excitatory,used to control our muscles

  -GABA-inhibitory, main inhibitory neurotransmitter used in brain

  -dopamine- both, controls our responses to rewards

  -serotonin-both, controls response to mood
• sensory neurons


  -pick up info from our sensory receptors

  -sends info towards brain

  -located near our sensory receptors
• motor neurones


  -carry info from brain to muscles
• relay neurones


  -process and transform sensory info

  -can form synapses w both sensory and motor neurons
• sensory neuron


  function- carries messages from peripheral nervous system (sensory receptors) to brain and spinal cord

  structure- long dendrites short axons, coating on axon called myelin sheath

  location- peripheral nervous system
• relay neurons


  function-transfer info from sensory neurons to other interconnecting neurons or motor neurons

  structure-short dendrites short axons

  location-most in brain and spinal cord
• motor neurons


  function- carries messages from CNS to effectors such s muscles or glands

  structure-short dendrites long axons

  location- Their cell bodies may be in the central nervous system but their long axons form part of the peripherals nervous system.